Rias Gremory is the main female protagonist of High School DxD. She is the next heiress of the Gremory Clan after her older brother, Sirzechs, took the title of Lucifer. She is the only daughter and youngest child of Zeoticus and Venelana Gremory, the aunt of Millicas Gremory, and the cousin of Sairaorg and Magdaran Bael. She is known as the Crimson-Haired Ruin Princess. She is a first-year college student at Kuoh Academy, the former President of the Occult Research Club, and the school's number-one beauty, as well as one of Kuoh Academy's Two Great Ladies alongside Akeno Himejima.
Rias is a beautiful young woman with white skin, blue eyes (blue-green in the anime, season 1-3) inherited from her father, Zeoticus, and a buxom figure. Her body measurements are [B99-W58-H90 cm] [B39-W23-H35 in]. Her body weight is [58 kg] [128 lbs]. Her most distinctive feature is her long, beautiful crimson hair which she also inherited from her father, that reaches down to her thighs with a single hair strand (known in Japan as ahoge) sticking out from the top. Her hair also has loose bangs covering her forehead and side bangs framing her face. Rias' height is 172 cm. (5 feet 8 inches), making her one of the tallest female characters of the series.
Although Rias has worn various types of clothing throughout the series, her most commonly worn outfit is the Kuoh Academy girls' school uniform, which consists of a white long-sleeved, button-down shirt (short sleeves for spring/summer), with a black ribbon on her shirt collar worn under a black shoulder cape and a matching button-down corset, a magenta skirt with white accents, and brown dress shoes over white crew-length socks. Rias also tends to wear seductive lingerie and thongs, especially when she has a desire to sleep with Issei.
On some rare occasions, Rias wears glasses when she's deep in thought, as she feels they make her mind work better despite having perfect eyesight.
Rias is a very kind and compassionate optimist, especially to her servants and people close to her. She gets angry and violent whenever people insult her or her peerage, showing a fiery side to her. This also plays into the fact that she dislikes cruelty towards people, as shown with her disgust over Marius Tepes, who abused his own sister for his own benefit, and how she killed the Fallen Angels, such as Mittelt, Dohnaseek, Kalawarner, and Raynare for their cruel treatment of Issei. She thinks of Issei as a special person and always gets jealous when girls are around him, becoming a totally different person when she sees him and other girls together, or when it comes to training. Despite her mature stature like a woman, Rias tends to act her true age and become frustrated whenever girls flirt with Issei.
She is proud of her family's name, but she does not like being seen as Rias of the Gremory Family. The reason for her living in the human world (as revealed in Volume 2 of the novels) is because there, everyone sees her as Rias, not as a Devil or as the Crimson-Haired Ruin Princess. Despite being seductive like Akeno, both of the girls are still innocent to love, as both of them become their age whenever around Issei or on a date with him.
She enjoys teasing Issei and Asia (from Volume 3 of the novels onward), but at the same time makes it clear (to Asia or any girl) that Issei is hers, and she does not want to share him at all (It is revealed in Volume 3 of the novels that the Gremory Family and their servants are beings with extraordinary affection among the Devils, so Rias is no exception). She has no problem with showing Issei her breasts or sleeping naked with him (which she always does according to her and she claims she can't sleep without being nude or without Issei).
After becoming Issei's girlfriend, Rias begins to show more confidence in her relationship with Issei and is no longer jealous or angry when Issei is with other girls like she previously was, even accepting Issei's dream of having a harem and letting the girls have dates with him. However, Rias still shows some signs of jealousy such as when Issei doesn't spend enough time with her, but still believes in him and loves him. Like Akeno, Rias shows a sign of dependence toward Issei (possibly lesser than the former) as Rias will lose her will to fight and lead.
She holds her older brother, Sirzechs, in high regard (despite her older brother's antics of being a siscon) because she deeply cares for him. When she was a child, she was entirely dependent on him and held him in admiration, while also feeling inferior to him at the same time.
Rias is the daughter and second child of the Gremory Family. She became the heir after her brother, Sirzechs, became the Satan Lucifer, losing his right as heir to the house. After being announced as the heiress of the Gremory Clan, Rias was eventually placed into an engagement with Riser Phenex. When she was a child, she was attacked by a camel for making fun of it, which caused her to have a strong fear of camels ever since. Just seeing imagery of a camel is enough to trigger her fear, as shown when she gets frightened seeing her clan's mascot, which is a camel.
Prior to the series, Rias has reincarnated Akeno Himejima, Koneko Toujou, Yuuto Kiba, and Gasper Vladi as members of her peerage. Rias met Akeno, her Queen, first servant and best friend, in Japan, saving Akeno from being killed by her fellow Himejima Clan members after Akeno accidentally entered Heinrich Cornelius Agrippa's territory. She then met Koneko, her second servant, after her brother rescued Koneko from being executed, leaving Koneko under Rias' care. She later reincarnated both Yuuto and Gasper, the former who died after being a part of the "Holy Sword Project" and the latter killed by Vampire hunters.
She entered Kuoh Academy two years before the series along with Akeno, Sona, and Tsubaki, reviving the abolished Occult Research Club which is used as a base for her servants and became its president. Rias and Akeno went to the Kyoto trip during their second year, Rias enjoyed every moment of it, however they didn't plan a proper scheduled and therefore there were places that she wasn't able to visit like the Nijou-jou, Rias was so upset that she stopped her feet at the railway station. Also during their second year, Rias and her club organised a haunted house for school festival, she even used real ghosts as she requested friendly Youkai looking for jobs to plan the decorations. This however got them in a lot of trouble with Sona who scolded them for using the real thing.
She revives Issei as her servant after the latter was killed by the Fallen Angel Raynare (then as Yuuma Amano). She later saves Issei while he was being attacked by another Fallen Angel, Dohnaseek. Badly injured and in need of medical assistance, she brings him back to his house and spends the night healing his injuries. The next day after school, she introduces Issei to her other servants as well as welcoming him as the newest member of her group. She saves him a second time from Freed Sellzen along with the other members of the Occult Research Club. When Issei goes to the abandoned church to rescue Asia Argento, Rias helps Issei indirectly by killing three of Raynare's Fallen Angel allies before terminating Raynare herself. She then revives Asia as her Bishop to Issei's delight.
At the beginning of Volume 2 after the usual daily training with Issei, Rias informs a shocked Issei that Asia will be staying with him, successfully persuading Issei's Parents that Asia's stay is for bride training, making them happy. Rias later goes to Issei's room during night time, attempting to have Issei take her virginity in hopes of breaking her engagement. The attempt, however, was stopped with the appearance of Grayfia Lucifuge, Sirzechs' Queen, who scolds Rias for attempting to break off the engagement set by her brother and father. When Rias' fiancé, Riser Phenex, appears in the Occult Research Club, Rias, who was still unsatisfied with the engagement, agreed to have a Rating Game with Riser under the condition that should Rias win, the engagement will become invalid, and should Riser win, Rias would be forced to marry Riser immediately.
In preparation for her Rating Game with Riser, Rias sets up a training camp in the mountains for Issei and Asia who both lack fighting experience. During their training in the mountains, Rias starts to develop strong feelings for Issei. On the day of the Rating Game, Rias faces Riser in a replica version of Kuoh Academy set up in a dimensional space. While the battle initially went well for Rias' team, they ultimately lost due to the lack of people on her team, surrendering after seeing Issei being beaten to near-death, yet still standing, trying to fight for her. She was later seen at her engagement party in the Underworld, which was interrupted by Issei who came to challenge Riser one more time with Rias' engagement on the line, with Issei successfully winning this time. After Issei helps to break off the engagement between herself and Riser, Rias falls in love with Issei and kisses him for the first time. She moves into Issei's house after the incident with Riser.
In Volume 3, Rias introduces her new servants, Issei and Asia, to the Student Council members led by Sona Sitri, a pure-blooded High-Class Devil from the Sitri Clan who is her childhood friend and rival. Issei noticed a change in Yuuto after looking at Issei's childhood photos, one of which was taken with his childhood friend, Irina Shidou, with a Holy Sword visible in the background. Rias then explains Yuuto's past to Issei and was greatly disappointed when Yuuto left her to seek his revenge after seeing both Xenovia and Irina. She and Sona eventually found out the alliance Issei, Koneko and Saji made with the church duo to destroy the Excaliburs, punishing the two of them for their actions. When Kokabiel, one of the leaders of the Fallen Angels, announced his war declaration against both the Gremory and Sitri clans who are attending the Kuoh Academy, Rias gathers all her servants (except for Yuuto who is still missing) in an attempt to fight back while having the Sitri Group as support. During the fight, Kokabiel summoned out many Cerberus to battle the Gremory Team but was defeated by the combined effort of the Gremory Team and Xenovia who arrived at the battlefield. After Yuuto attained his Balance Breaker and broke the Excalibur with Xenovia's help, the Gremory Team was then forced to battle Kokabiel himself but were easily overwhelmed by the Fallen Angel Leader and was in despair until the sudden interference of Vali Lucifer who came to retrieve Kokabiel under Azazel's order. Following the battle, Rias reincarnated Xenovia as her second knight after the latter asked her after she found out that the God from the Bible is dead.
In Volume 4, after Issei reports on his meeting with Azazel much to Rias' anger on Azazel's action, they are surprised at the sudden appearance of Rias' brother, Sirzechs Lucifer, who came for Rias' class observation, telling Rias that Azazel won't do anything drastic like Kokabiel. Rias later unseals her other Bishop, Gasper Vladi, a half-Vampire who she revived as a Devil using a Mutation Piece, after receiving orders from Sirzechs. During the peace talks between the Three Factions, Rias was asked to report the events that happened during Kokabiel's attack and assisted when the Khaos Brigade attacked using castling to rescue Gasper who was used by the terrorists. Near the end of Volume 4, Rias is seen troubled when Azazel introduces himself as the adviser for the Occult Research Club, getting angry at Azazel when he suggested taking Issei on a virgin graduation tour, telling Azazel that Issei's virginity is under her watch. She also decided to renovate Issei's house after Akeno, Koneko, and Xenovia moved into the Hyoudou Residence.
In Volume 5, Rias returns to the Underworld for the Young Devils Gathering in which they will fight in Rating Games. Before the opening ceremony for the Young Devils Gathering, Rias introduces her cousin, Sairaorg Bael, to Issei, telling him that Sairaorg is the strongest young Devil. On the opening ceremony of the Young Devils Gathering, all the six chosen young Devils are asked to step up and speak out their dreams. The ceremony ended with Sirzechs announcing the first match for the Young Devils Gathering that is between Rias and Sona. During the party set up by Sirzechs Lucifer for the young Devils, Issei and Rias notices Koneko rushing out of the party hall and follow pursuit, seeing Koneko's older sister, Kuroka, who attempted to bring Koneko back with her, with Rias objecting, claiming that Koneko is her Rook and she won't allow anyone, even Kuroka, her biological sister, to take her away. Feeling troublesome, Kuroka then uses a special mist that affects both Rias and Koneko, limiting their mobility. Despite so, Rias was still useful in the fight, as her breasts were used by Issei to attain his Balance Breaker. She later faces her childhood friend and rival, Sona, for her first match in the Young Devils Gathering and won due to Issei and Yuuto's aid but was unhappy with the victory because she lost four of her servants and was unable to display the full potential of her group. Near the end of Volume 5 while on their way back to the human world, the team was surprised to see Diodora Astaroth who introduces himself.
In Volume 6, she was scheduled to face Diodora for her second match in the Young Devils Gathering. before so, Diodora even came to their club room offering to trade one of his servents for Asia but rejecting his offer to exchange. During the day of the Rating Game, Rias and Diodora's supposed Rating Game did not occur due to the Khaos Brigade's interference and the revelation of Diodora's alliance with them. After Diodora kidnaps Asia, Rias and her peerage go to rescue her while fighting through Diodora's peerage, both Rias and Akeno defeated his Queen and both Bishops. They arrived to his destination where Rias allowed Issei fight Diodora alone and free Asia, even so Asia had suddenly vanished as Shalba Beelzebub had sent her to the Dimensional Gap. During Asia's supposed "death", Issei's negative feelings made him activate his Juggernaut Drive and go berserk in attempting to kill Shalba. Vali and his team arrived and happened to have rescued Asia, Vali suggested that they needed to stimulate Issei's heart to calm him down. That was when Irina came with a recording of the new song written by Azazel and her brother, allowing Issei to regain part of his sanity before having Rias use her breasts to cancel the Juggernaut Drive. Rias and her friends where later seen during the sports festival cheering for Issei and Asia on their three-legged race. After the race, she told Asia to take Issei behind the gym to heal him as well as whisper in her ear to give her motivation to confess to him.
In Volume 7, Rias and her club members were in a big hall located at the basement of the Hyoudou residence as Azazel showed them a tokusatsu of the Oppai Dragon show based off of Issei that's currently popular with kids, staring her character as the heroine known as the Switch Princess. Rias express her embarrassment and displeasure of being publicly called Switch Princess in the Underworld since her breasts were what caused Issei's transformations. She and the other girls then glared at Issei whom Akeno was hugging from behind while reminding him of the date he promised. At school, her club were discussing what activities to do for the school festival until they all got a call to deal with the Hero Faction of the Khaos Brigade in town, after fending off several members with Sacred Gear. That night, Rias and Asia overheard Issei's talk with Koneko involving making babies and calling her a bad influence, she and Asia then spend the night in his bed interrogating him. The next day, Rias and several of her servants went to spy on Issei and Akeno's date. Akeno took Issei manage to escape Rias and the others, much to Rias' displeasure despite the date ending abruptly due to the two encountered the Norse Chief God Odin, Rossweisse, and Baraqiel, Akeno's father. The Occult Research Club are then asked to served as Odin's bodyguard until his meeting with the Japanese gods to form an alliance. Several days later, they are then attacked by Norse's Evil God Loki who came to kill Odin and create Ragnarok, Loki was able to overwhelm them with his son, Fenrir, but decided to retreat after seeing the Vali Team, claiming that it is enough to see the Two Heavenly Dragons together. Both two teams eventually decided to work together to defeat Loki and Fenrir, asking the advice of one of the Dragon King's, Midgardsormr, on how to defeat Loki and Fenrir, although Rias expressed her hatred towards Bikou for being the one who coined her the name Switch Princess. The night before the battle, Rias comforted Issei who was feeling nervous about the upcoming battle, the two then shared their third kiss. Loki was eventually defeated in conclusion of the battle. Later in the Club room, Rias recruited Rossweisse into her Peerage as her second Rook, who was abandoned by Odin. Rias, Asia, Koneko and Xenovia were then angered at Issei when Akeno had kissed and confessed to him in front of them.
In the Extra Life of Volume 8, Rias and Issei went to the Underworld and underwent a ceremony at the Ruins of Connection to test their love for each other. Issei, however, does not realize the purpose of the ceremony. Throughout the ceremony, Rias and Issei faced four trials set up by the Satan Rangers. In the first trial, Issei and Rias had to dance; in the second trial, Rias and Issei were tested on table manners; and in the third trial, Issei and Rias was tested on the history of the Gremory Clan and general knowledge in the Underworld, all of which they successfully passed before moving to the final trial. In the final trial, Issei was forced to fight Sirzechs/Satan Red and was completely overwhelmed by the latter until Grayfia's advice on using Rias' breasts as a power-up allowed Issei to use one final Dragon Shot but still lost after Sirzechs negated the attack and retreated after Issei loses consciousness. Despite so, they passed the trial and Issei became officially as a suitable candidate husband.
Volume 9, Rias had just gotten out of the bath to find that Akeno, Koneko and Asia where clinging to Issei in his room, she was furious at her servants for disobeying her and claiming that he was theirs, she yelled in objection saying the he was hers. Rias and her club members were audiences for Issei's mock battle with Sairaorg. Just as everyone was about to leave for their trip to Kyoto, Rias gave them passes for Devil to enter holy places such as shrines as well as a badge to Asia to also Issei to use Promotion. After adjusted Issei's collar, Rias leaned in and expressed that she will also be lonely without him and kissed his lips before seeing him off.
Rias was briefly mentioned by Azazel as being busy and cannot help Issei and the others in Kyoto with their battle against the Hero Faction as she is in the Gremory territory and fending off the assaults incited by the Old Maou supporters, along with her mother and Grayfia. She was then summoned to Kyoto and got her nipples poked by Issei for him to power up and use Illegal Move Triaina. After the trip and everyone's return home, Rias, Akeno and Koneko were angry at them for not informing them of the situation with the Hero Faction.
At the beginning of Volume 10 of the light novels, Rias and the rest portrayed their characters in for the Oppai Dragon under her brothers request. Soon after, her mother, Venelana, encourages her to push her relationship further with Issei and take the lead in his harem, in which Rias would attempt to seduce Issei. She and Issei payed a visit to Sairaorg and his mother who had been ill for along time. The Gremory Group and Sairaorg's team had a press conference where they face questions from reporters, some in particular asked Issei if he will be pressing Rias' nipples during their upcoming match which greatly embarrassed them both.
Following her mother's advice, Rias indeed tried to seduce Issei by trying to have sex with him in the sauna room of the Hyoudou Residence, but she got upset when Issei could not call her by her name and she left in tears. At the club room, after the call with Ravel's mother where she requested Issei to look after her daughter, Rias asked Issei about how he felt about about all the other girls, yet still only refereed to her as "President" instead of her name which greatly upset her to tears as she ran out with Asia chasing after to console her.
She later faced her cousin, Sairaorg Bael, in a Rating Game which Rias' team won after Issei beats Sairaorg, making Rias the winner of the Young Devils Tournament. Back home, the Occult Research Club decorated their club room as a haunted house for the school festival. At the end of the same volume, Issei finally confesses and calls her Rias for the first time instead of President. She sheds tears of joy and tells him that she feels the same way and the two officially become a couple. Just as they were about to kiss, their moment was interrupted however as everyone else was spying on them, causing her to be angry at them and blamed Issei for picking the wrong moment.
In Volume 11, she accompanied Issei, Akeno, and Yuuto during their Middle-Class promotion test with Issei asking her out on a date should he pass the test. While Issei and the other two are resting the after the test, they are ambushed by Cao Cao and Georg who came to steal Ophis' powers. The battle ended with the Gremory and Vali Teams losing to Cao Cao and Ophis' powers stolen. Both teams were then attacked by a legion of Grim Reapers and Siegfried. They eventually overcame the situation by having Issei use Rias' breasts to replenish Issei's magic and successfully force their enemy to retreat. At the end of Volume 11, while waiting for Issei to return from the crumbling dimension, Rias like the rest of the Occult Research Club was surprised that only Issei's Evil Pieces returned, and was shocked to find out that Issei died.
In Volume 12, Rias, who was still in shock at Issei's "death", locked herself in her room and was not responding to anyone until Sairaorg came and talked some sense into her. She and her peerage later goes to the human world to meet with the creator of the Evil Pieces, Ajuka Beelzebub, to have him check on Issei's Evil Pieces and are surprised to see the Khaos Brigade's Old Satan Faction and Hero Faction coming to see Ajuka, intending to form an alliance with the latter which was rejected as Ajuka finishes off the Old Satan Faction members, leaving Siegfried to the Gremory Team. Like the rest of the girls, however, Rias was unable to display her usual strength until Issei's Evil Pieces glow and convey his feelings to the team, allowing them to regain their determination to fight. After Ajuka confirms that Issei's soul is still alive she and the rest of the Occult Research Club were extremely happy, looking at the news to confirm the current status of the Underworld until hearing that the Sitri Group is engaging the Khaos Brigade in the town area as they head out to battle the Khaos Brigade. After Issei returns, Rias inserts back Issei's Pawn Evil Pieces into his body kissing him. At the end of Volume 12, Rias congratulates Issei for passing his Middle-Class promotion test, asking him out on a date as promised before the test.
In Volume 14, Rias and her peerage meet the director of the Magician Council, Mephisto Pheles, regarding their pact with the Magicians. Rias also mastered a new finishing attack during her training with Akeno. After the negotiation with the Carmilla Faction from the Vampire side, Rias was angered by their means of obtaining Gasper by using the peace negotiations of the Three Factions to force them to hand over Gasper or risk allowing the Devils to lose trust on their intentions of achieving peace. She later decides to leave for Romania with Kiba and Azazel in order to learn more about Gasper's ability.
In Volume 15, Rias accompanied by Kiba were staying at the House of Vladi until a Vampire from the House of Vladi asked them to meet the current leader of the Tepes Faction, Valerie Tepes, much to the surprise of the two.
In Volume 16 Rias, along with Yuuto, were confined in the Tepes castle in due to the coup d'etat of the anti-government group in the Tepes Faction that are helped by the Khaos Brigade in the shadows. She later reunited with the Occult Research Club members after Azazel told the group to come to Romania as they met the new "King" of Tepes Clan, Valerie Tepes and the new mayor of the town, Marius Tepes. Rias and the group were angered by Marius' action where he doesn't even hide from them the fact that he is indeed controlling Valerie's emotions and actions. After the meeting, Rias and the group were shocked at the appearance of Rizevim Livan Lucifer and Lilith. She then participated in the attempt to stop the extraction of the Longinus, Sephiroth Graal, from Valerie and save her; fighting the enhanced Vampires and Grendel along the way and in doing so, used her new move, Extinguished Star, to injure Grendel. Rias later teamed up with Akeno in defeating the mass-produced Evil Dragons that were rampaging in the Carmilla's castle town. After returning from Romania, Rias participated in the meeting for the formation of D×D. After the meeting, Rias proclaimed that they need to stop Rizevim's violent acts and they need to get stronger in order to do so.
In Volume 17, Rias was asked by Rossweisse for permission to have Issei act as her boyfriend due to a lie she told her grandmother, Göndul. Rias and the Occult Research Club went to the Underworld and visit the newly built Auros Academy, which was eventually attacked by Qlippoth, Rias, Sona and their respective Peerage team up to defend the school. Later Rias and Issei fought against Euclid who had captured Rossweisse due to resembling his sister Grayfia, they managed to save her and defeat him and have him arrested. In the aftermath, Rias and Issei help clear the rubble when he asks to talk to her more casually during their private times which gladly accepts, their moment is interrupted by Sona who jokingly offered to build a memorial for them here.
In Volume 18, Rias and Issei were watching the Oppai Dragon show, after that she and the rest of the club members went to Heaven to discuss the Christmas project that the alliance is working on with Michael. After the meeting, Michael informed them about the deaths of the Church officials and the presence of Evil Dragons found at the attacks. She is later seen along with the other girls observing the Interdimensional Room that Touji Shidou brought for Irina to be able to have sex with Issei without falling and commented on how revolutionary the room was. After Touji Shidou was attacked by Masaomi Yaegaki, the one responsible for the deaths of the Church officials, Rias and the Occult Research Club meet up with Zekram Bael, who revealed to them that he ordered with the permission of the Church the death of the exorcist Masaomi and the High-Class Devil Cleria Belial for being in a romantic relationship, in order to maintain the status quo that both sides did not want to disturb. Rias and the other club members helped defend Heaven, with the assistance of Cao Cao much to their surprise, from Qlippoth's sudden assault, he then proceeded to help Rias fight against Ladon where they managed to trap him inside a hole that was made by Cao Cao, allowing Rias to use her Extinguished Star of destruction, thus allowing her to defeat Ladon, Koneko then proceeded to seal Ladon's Soul inside one of the Jewels that she got off of Issei's armor in order to prevent his body from being restored by the Holy Grail.
In Volume 19, Rias went to Kyoto along with the other club members for New Year’s Day, where she and Issei meets up with Kunou and her mother Yasaka who greet their arrival. Rias tells Issei about a previous discussion with Yakasa about Kunou attending middle school at Kuoh Academy in the coming year. The two then head to the top of the shrine meet up with their friends who’re giving their prayers while noticing Xenovia suddenly kissing Issei. A few days later, at night in the Hyoudou Residence underground pool, Rias and Issei show to the members of their club, Vali’s Team, Dulio, Sister Griselda, Tobio and others their new technique too. She then requests Issei to rub sun lotion onto her back, which catches the attention of most of the other girls who also want to take turns in him rubbing lotion on them with Ravel sorting a schedule.
The next day, while the gang is going out, they are visited by Vasco Strada, one of the people leading a rebelling against the Church, he Rias a gives a challenge announcing a battle between them and the rebels in three days. Later on, Tannin paid a visit to the Hyoudou Residence, asking for their assistance in looking after an egg of a rare species of Spectral Dragon and is surprised to see that Crom Cruach is the one delivering the egg, it’s revealed that he is currently under Tannins care.
On the day of the battle against the Church rebels, they gain assistance from the Sitri group and Brave Saints. They split into two teams to defeat the rebel leaders, Vasco Strada and Ewald Cristaldi, with Rias leading the team to battle against Vasco. The battle against Vasco proves to be difficult as none of them are able to hit him even when Yuuto, Irina, and Arthur joined in, that is until Xenovia was able to beat him with both Durandal and Excalibur. They were about to arrest Vasco until he attacked by Walburga's sudden ambushed, she planned on taking everyone out with her army of Evil Dragons, however, the Dragons are soon immobilized by Rosswiese's barrier and her escape was cut off by Tobio. Rias and her team go up against Walburga who activated her Balance Breaker containing half the soul of Yamata no Orochi, everyone gave it their all against it until it was destroyed by Xenovia's new "Cross Crisis" technique and Issei finishes her off with his Crimson Blaster, resulting in her defeat and arrest. Rias and the others later heard the tragic news of Ravel having gone missing along with Raiser and Diehauser during their Rating Game.
In Volume 20, everyone is depressed over the disappearance of Ravel, including Raiser and Diehauser, they believe that Qlippoth is responsible with suspicion of the Champion also being involved. After bathing with Asia, Rias and her noticed Issei's Mother looking at a photo album, she tells them stories about Issei's childhood like the last time Issei went fishing with his Father. she then says while her son is perverted and stupid, he is still an honest person and entrusts him onto both of them. When they heard Ravel was now under Ajuka's care, The D×D members arrive at different dimension resembling a nighttime beach with two moons where they spot Ajuka next to Ravel who is in a bed barely conscious and assures them that Raiser was sent home safely by Slash Dog’s Team. Ajuka then explains to them about his secret creation from the general public known as the King Pieces and how some top-ranked Rating Game contestants have been using them, which was proposed by the higher-ups in the Underworld, a revelation that shocked everyone present. He then explains that while also having one in possession, Diehauser has only ever used his own strength, but reveals the champions involvement in stealing Agreas in order to pursue the truth of everything, another shocking truth revealed to everyone. Soon Ajuka receives a startling call and tells them to return home as Ophis is being attacked by an Evil Dragon.
Back at the Hyoudou Residence, Rias' group arrives to see Ophis unconscious on her bed and brutally injured from protecting the Dragon egg from Niðhöggr, who also kidnapped Issei's parents. Just when Kuroka and Le Fay arrive from the rest of Vali’s Team, they bring them info about the location of Agreas, the hideout for Qlippoth’s base. Later on, D×D prepares to strike back as they teleport to Agreas, with the Gremory team being the main force. Rias' group make their way through Agreas when they come across Niðhöggr, everyone began their attack on him with full force with Issei and Rias using their new technique that equips Rias with her own variation of the Scale Mail armor; Crimson Extinct Dragonar. However, all their efforts are useless as Niðhöggr recovers from their attacks using several vials of Phoenix Tears, which is until Crom Crauch appears and brutally beats Niðhöggr. Rias tells Issei to move forward along with Asia to find his parents.
In Volume 21, a week after Trihexa was unleashed upon the world, Rias along with the others and Issei's parents await his recovery in a hospital in the Underworld. When Issei wakes up, they're surprised to learn that due to the aftereffects of using DxD mode, he's unable to see, talk or even think about breasts as it would cause him pain otherwise. Sometime later when Issei is able to move again, both Rias and Akeno warn him to not push himself too hard. Their group headed to an island on the coastal waters of Japan where they join up with an army of different races from various factions to battle Qlippoth's army of Evil Dragons, fake Scale Mails and one of the bodies of imperial beast led by Apophis who are on route to their location. With Issei's assistance, Rias activated her Crimson Extinct Dragonar armor and fought alongside everyone. At the end of the war, after Sirzechs, his peerage and some of the other mythology leaders sealed Trihexa along with themselves, Rias is seen next to Sona who are both expressing their sadness and disappointment at their older siblings for leaving them so suddenly.
In Volume 22, Rias catches Akeno attempts to have sex with Issei, who joins them not wanting to be left out. They were interrupted by the arrival of Ravel and the Church Trio, with Ravel giving the news to Rias about the Rating Game World Tournament. After this, Rias kisses Issei's cheek and leaves with Akeno to find out more about the tournament.
On their next weekend off, Rias along with everyone from the Occult Research Club, Vali's team and Issei's parents went on a fishing trip on an inhabited island owned by someone related to them to them. She and Akeno assisted Issei's mother carrying the food and setting up setting up the parasol on the beach. After Issei had officially been promoted into a High-Class Devil, Rias had traded Asia and Xenovia into his peerage.
On the day of graduation, Rias goes together with Issei and Akeno to Kuoh Academy, holding Issei's arm while they walk. In the ceremony, she shed tears after Yuuto, Koneko, and Gasper started to call her variations of "nee-san" which she happily tip toed at the sound of. Rias then requested for Rossweisse be also transferred, while she was initially baffled by this, Rias hugged and assured her that she believed that Rossweisse will be able to release all of her potential the most by serving under Issei while in turn he will need her strength and support, which she accepted as the two shed tears. She then gets proposed by Issei which she tearfully accepted and the two become officially engaged.
Red Dragon Emperor of the Blazing Truth × White Dragon Emperor of the Morning Star: The True Dragon(s) of the Kuoh AcademyEdit
Rias and her current peerage attended the opening ceremony of the Azazel Cup along with new temporary members such as Mr. Black as her Pawn, Sellzen as her Knight and Valerie her Bishop for the duration of the tournament. She and everyone and witness Issei's teams late yet grand entrance through Ryuuteimaru with Rias saying to Issei that she won't lose to him. After Issei's match against Baraqiel, Rias started to bicker with Akeno after Issei confessed to her on who will take Issei's virginity.
In Volume 23, Rias had already achieved continuous victories over her matches, her next Rating game match was with an Ultimate-Class Devil when she shows off to everyone the improvement of both old and new members of her team. She easily overpowered the Ultimate-Class Devil who was already wounded from Crom Cruach's earlier attack, with most of the opposing teams peerage being forced to retire, the Ultimate-Class Devil had no choice but to surrender, thus adding another win to Rias and her team.
Rias and her servants were in the spectator room for related personnel observing Issei's Rating Game with Dulio. Rudiger was also present and discussed with her the strategies he thought of to be used against Issei such as exploiting Xenovia to help Irina which cost her the goal and caused her to berate herself, as well as trapping Issei in a bubble showing a recording of Gabriel in a swimsuit. Just when things were seemingly down for Issei's team, Xenovia wore her Crimson Destruction Dragonar armor, upon witnessing it Rias gave a bitter smile and questioned Rudiger whom remained silent if he had predicted this outcome. Rias was also able to figure the identity of Issei's Queen Bina Lessthan was in fact Grayfia Lucifuge.
On a later date, Rias payed a visit to the farm in Italy where Vasco Strada was under house arrest, to offer him a place on her her team for the tournament. While Vasco was intending to decline like all the others, Rias attempted to persuaded him by reaching out to the warrior in him to fight again, she then sweetens the deal by temporary restoring the old man to his youth via non-demonic means so as to not appose Vasco's faith. Further Rias teleported a long, slim briefcase, within it were two sword, one of which was the new Durandal II sword for Vasco created by Heaven, Vasco picks it up and slowly come to accept her offer. Vasco warned Rias that he will cut down her future husband should they face each other, she simply replies that it's just something he will have to overcome, to which they saw it as part of Issei's groom training.
Rias then recalls back to when she confronted Grayfia after Issei's match, Grayfia revealed to her that she intends to make Issei a Satan, believe that this will eventually be the intention of the entire Underworld and plans to support him in this endeavor. Rias stated that she will win even against her, to which Grayfia is glad to hear from her sister-in-law.
Vasco then question the second sword, Rias replied that it was a crimson sword that Heaven had gifted her on her engagement as a blessing, but since neither her or Issei can master it, she instead plans to pass it on to her future children. Agreeing with the idea, Vasco then desires to bless her children should he live long enough, though Rias obviously notes that it be a lot of trouble to bless Devils. As the two were catting, Rias got a call from Akeno on her phone, she received shocking news that The Champion Diehauser Belial has been temporarily released for the tournament.
In Volume 24, the Gremory group visited the school swimming pool to relax, Rias all of Issei's fiances were arguing over who should he rub sun tan oil first. She removed her top declaring as the first to strip to go before the others, Xenovia took it further and attempted take Issei to the storage room to make babies, but Rias and Akeno were against it, Xenovia then challenged Rias to a swimming contest to see who gets Issei. Rias stopped swimming as she and everyone caught word that all their parents and guardians have met up at the Hyoudou Residence. Upon arriving home, Rias and everyone learned the reason for all of them gathering was to discuss plan for the wedding ceremonies for each of Issei's fiances, upon hearing this the girls made their requests, Rias' wanting to hold hers in Kyoto as she showed her parents a wedding brochure she had in hand. Vasco then appeared before them wanting to give his blessings at that time as a priest, everyone from Issei's team was surprised when Rias announced that Vasco will be participating in the tournament with her team. Everyone then sat in the living room listening to Issei's father telling stories about his grandfather.
Evening on the following day, Rias had just heard about the attack from the Grim Reapers while having also heard a similar situation from Sairaorg with some unidentified Devils causing riots, they then received a message from Tobio who had relevant info on the topic. Rias, Issei, Ravel and Rossweisse met with Tobio at the bar he worked the next day, there they also met with Lavinia whom Issei showed lustful intend, causing her and the other girls to scowl at him. Cao Cao then appeared before then with the info Tobio called everyone for, they learned that there's a faction of Grim Reapers led acting behind the scenes of the tournament, the unidentified Devils were somehow confirmed to be pure blooded and Grim Reapers led by Hades were spotted during their riots as well as were unrelated to the ones that attacked Koneko. Back home at the VIP room, Ravel suggested that they needed to know more about Koneko's past to find out why she became a target, with Sona and Tsubaki's assistance they recommended visiting the mirror Youkai who can communicate with those who have parted. As everyone used their connections to find it, Rias reminded Issei of the branch house of Naberius that took in Koneko and Kuroka, informing him that they were obsessed with a certain dark research which against the main family’s wishes continued to carry out dubious experiments.
Rias invited Issei's team for a training session to help her for the upcoming match against Vali's team, she stood beside Issei watch Gasper and Ouryuu's mock battle, noting two will make good rivals for each other. Suddenly they were attacked by Grim Reapers who came back to abduct Koneko, as they fought Issei questioned their movtives but only confirmed that they are following only Thanatos orders independent from Hades. However the Reapers had no luck obtaining their objective with the late arrival of Vasco and Crom Crauch and their leader defeated, they resorted to retreating. Back home they had Bennia call her father to find additional info on Thanatos. Rias, Issei, Akeno and Ravel transported to an old shrine that was situated deep in the mountains of the Tohoku region in Japan to meet with the mirror Youkai. While Sona introduced the current Ungaikyo, it stated that he cannot fulfill their request due to complications but was immediately persuaded when Magari also arrived who also wanted to know the details of Koneko's past. Although the Ungaikyo informed them that the soul of Koneko's father had been placed under seal, Magari had ever one prepare a tub that would allowed her to negotiate with Great King Enma but still proved to be difficult as the seal was was done by a magician using demonic energy, she added that they could get some leeway when they get the cooperation of a Satan and a magician’s association. As Rias, Akeno, Ravel, Sona and Shinra used their own respective channels to seek help, while Issei waited, Rias suggested that he could use the Ungaikyo to can call his late grandfather. Issei soon then introduced Rias to as one of his fiances, the old man admired hers and Akeno's chest while recalling Issei wanted to marry an "onee-san" with big breast when he was younger. Their communication was about to be cut off, he assured that should anything happen he will come over to help him and leaves his parting words to Issei to feel up as many breasts as he can.
With the cooperation of the other factions, the Ungaikyo was able to bypass the seal and summon the soul of Koneko and Kuroka's father but was having trouble remembering anything, although when Rias questioned him regarding Koneko and Kuroka he slowly began recall his memories of his past and Nekomata lover Fujimai. They learned that the scientist had been experimenting on artificially creating Super Devils for the branch house of Naberius as well as someone of Nebiros which greatly shocked everyone, Issei in particular was angry at the fact that he did not have mutual feelings for Fujimai or even aware that the girls she birth were his. Furthermore, they learned that one of Koneko's hair clip ornament that was a memento from her mother had the research date on his experiment, thus explaining why she was being targeted. As their line with him was about to be disconnected, the man begged to know if his research had been successful before being cut off. After returning home, they informed all their comrades everything they had discovered while omitting any mention of her parents to Koneko, she willingly gave her hair clip that was lend to Ajuka. Le Fay and Kuroka had just returned from the depths of China’s Youkai world, they soon informed Kuroka that her sister was being attacked by Grim Reapers and will also come after her, Rias then talked to her in private about what they uncovered about her parents. Rias had come down to bathe but didn't enter as she overheard Issei and Koneko having a deep conversation, Koneko noticed her as Rias apologized for unintentionally eavesdropping, Koneko left the bath and gave her space alone with Issei. As Rias entered the bath with him, Issei also told her that he will be cheering for her, Rias winked as she undauntedly said not to hate her if she were to defeat his rival. They were about to kiss when the Church Trio had also came in and unintentionally interrupted the moment, Issei and Rias simply looked at each other and laugh.
On the day of Rias and Vali's match at the Fafnir Stadium within the Fallen Angels’ territory of the Underworld, the game played was announced as Board Collapse which implied that the field will begin to collapse starting from both ends. As the game goes on, Issei and all their comrades acted as guards around as Tobio suspected that the Grim Reapers will attack again.
During the match, Rias was approached by Vali only for Crom step in as he wishes to be his opponent. Rias tells Crom that in this tournament he will be replacing Issei and will allow him loose to fight Vali. After leaving Crom to Vali, Rias and Gasper sees Fenrir in a rooftop of a building and they prepared to face him. Rias and Gasper were overwhelmed by Fenrir’s incredible speed and watched as he gets enveloped in his gray aura as he returns to his prime state. Rias and Gasper chanted together and Rias gets cloaked by Gasper’s darkness similar to the armors of the Longinus and calls it Forbidden Invade Balor the Princess. Rias attempted to freeze Fenrir’s movement but he managed to release himself using his gray aura, Rias teleported to the building and unleashed her power of destruction with combining it with the power of darkness thus destroying the building while launching it at Fenrir but managed to dodge the attack. Rias started to lose stamina in her Balor form as she continued to fight Fenrir, but Gogmagog arrived to assist him and shoot her with lasers forcing her to use her demonic power to deflect them. Rias and Gasper watched as Gogmagog destroys the building where Valerie is and Vasco arrives to assist Rias in her fight against Fenrir and Gogmagog. Gasper separates himself from Rias as she reaches her limits and tells her she needs to announce her retirement, much to Rias’s protest. Rias begrudgingly announces her retirement, this allows Vali and his team to win the match.
Rias gets disappointed with her loss and losing front of Issei but he comforts her that she puts up a fierce fight against Fenrir. She gets approached by Koneko who decided to use her real name Shirone from now while also using Toujou as her surname, with Rias agreeing to her wish. Rias later agreed to Kuroka also wanting to inherited Toujou as her surname. Rias watches as the girls fight over Issei’s kiss and believes if she and Issei kissed she will eventually recovers from her injuries.
In Volume 25, Rias been sending her protest to Asgard because of the Norse higher-ups decision to have Rossweisse marry the current chief-god Vidar due to his family’s lineage is in crisis. After the argument the Asgardians agrees about not having them engaged but still want Rossweisse to attend the marriage meeting. During at college of Kuoh Academy, Rias and Akeno noticed Issei paying them a visit and introduce him to their new friends in college as their boyfriend, shocking Issei. Rias reveals she doesn’t agree with the marriage meeting between Rossweisse and Vidar but Issei is currently her master and asked him what is Rossweisse to him and Rias goes to do the bill, leaving Akeno to discuss with Issei.
Rias walks into Issei’s room and informed him and his team that been summoned to the vip room by Ajuka in order bring both teams to the training ground in a smartphone game called Belzebut for them get stronger. After both teams were taking a break, Rias started to think about Issei and Rossweisse who was blushing after Ravel says he was training for her sake and with Rias saying he forcefully took her back after she was engage. She was unable to return to the Hyoudou Residence because had things to do in the Underworld so she stayed there with Akeno.
Rias and her team journeyed together with Issei team to Valhalla in Norse mythology to watch and cheer for them facing Team Leisure of the Kings. Rias and her team celebrated at the Hyoudou Residence for passing the preliminaries along with rival teams. When the girls fight over Issei, he was sent flying to Rias’s chest and she congratulated him for entering the main stage of the tournament and he also congratulated to her as well. She reminded Issei that if they get a match she won’t go easy on him, but he’s a aware and says give their best and the two expressed their love for each other.
Powers & AbilitiesEdit
Demonic Power: Rias has exceptional demonic power even for a High-Class Devil. Azazel noted that even without training, Rias has the potential to become a Devil of the highest class relying solely on natural talent alone. Upon utilizing her demonic power of destruction's, the surroundings will gradually shakes to the point that her abilities is comparable to an Ultimate-Class Devil. In Volume 23, Rias completely overwhelmed an ultimate-class Devil, who was wounded by Crom Cruach’s initial blow state. When combined with her Forbidden Invade Balor Princess form, Rias is able to keep up with Fenrir in eighty percent of his original form.
- Power of Destruction (滅びの力, Horobi no Chikara): A type of demonic energy that allows her to release energies that can disintegrate matter, both living and inanimate, with relative ease. She is further able to control the shape and power of the technique such as creating multiple softball sized bullets to lessen the destructive force yet increase the range of her attack.
- Extinguished Star (消滅の魔星（イクスティングイッシュ・スター, Ikusutinguisshu Sutā, lit. "Demonic Star of Extinction"): Rias' ultimate one-hit kill technique created from the change in Rias's demonic power due to the influence of Issei's power. Rias manipulates her Power of Destruction into a compression of unimaginable amounts of demonic power; takes the form of an enormous sphere with a mixture of crimson and black aura radiating from inside of it that launches it toward her enemies in a slow velocity. It has the ability of a magnetic force; pulling the enemies towards it and get disintegrated by the latter similar to a black hole. Its destructive power is stated to surpass the speed of the retiring system in the Rating Game.
Expert Magician: Rias is also shown to be proficient in using magic such as the ritual to drain energy from Issei's left hand to let it appear human again, teleportation magic, healing spells with the most fatal being restored as she makes skin to skin, as well as defensive magic to protect herself as well as her servants from powerful attacks and create several layers of defensive barriers to protect from explosion aftershock of Katerea self-destruct spell. Rias can also use magic communication circles.
Forbidden Invade Balor the Princess: A combination technique between herself and Gasper Vladi, where Gasper melts into his shadow and fuses with her shadow where he covers her entire body in darkness. The result is a form of Rias appearing as a dark beast in the shape of a human enveloped in deep red aura of destruction, as well as a third eye with a deep red pupil on her forehead. The form resulted from the inspiration of Sairaorg's Balance Breaker, supplemented with her Crimson Extinct Dragonar. In this form, her third eye can freeze opponents in time. She can submerge in shadows and reappear out of others; her Power of Destruction's power is greatly increased with the infusion of the power of darkness, and she can also stop her own attacks and manipulate them to change the trajectory. The form, while still incomplete, exceeds Satan-class power, and is able to casually destroy an area with a radius of a few hundred meters filled with skyscrapers.
Enhanced Durability: Rias has shown great tolerance to damage and pain, she was going continuing to fight Regulus and remain in the rating game despite the intense blood lost.
Oppai Beam: Rias has gained the ability to project a red light from her breasts, which recharges Issei's energy. Each use of this power causes her breasts to temporarily shrink in size, which makes Issei cry even though it's sometimes necessary. Her breast size will restore itself after a few days of rest.
Expert Tactician: Though outsmarted several times throughout the series, Rias has proven herself to be an excellent tactician and has saved her team along with others many times due to her profound intellect and her ability to handle unexpected difficulties calmly.
Memory Alteration: Rias has shown that she has skills in memory alteration using it on Issei's Parents.
Stealth Expert: Rias has learned how to mask her presence to allow to remain undetected, as a way to sneak behind and surprise Issei without being noticed.
Flight: Being a Devil, Rias can fly using her wings.
Crimson Extinct Dragonar (深紅の滅殺龍姫, Kurimuzon Ekusutinkuto Doragunā lit. "Death Scarlet Destroyer Dragon Princess"): A combination technique between Rias and Issei. Issei uses his Red Wyverns and they sync both of their auras and the Wyverns attach themselves to Rias to create her own female version of Issei’s Scale Mail. The armor acts just like Issei's, boosting Rias's abilities and giving her the ability to utilize Boost, Transfer, and Penetrate until she reaches her limit.
Unnamed Red Sword: A crimson sword able to be used by a devil, which Rias received from Heaven as a blessing after her engagement to Issei. She plans to pass it on to their future children.
- (To Issei upon death) "So you were the one who called me." (Volume 1, Life 0)
- (Introducing herself to Issei) "My name is Rias Gremory. I am a Devil. And I am your Master. Nice to meet you, Hyoudou Issei-kun. Can I call you Ise?" (Volume 1, Life 1)
- "There's one last thing you should never forget, Ise. Even a [Pawn] can take down the [King]. This is basic in chess. This truth also applies to the Devils' chess pieces. You can become stronger." (Volume 1, Life 4)
- (To Issei) "Geez... You're an honest kid with perverted thoughts too. Ufufu~♥" (Manga, Chapter 22)
- "Now my adorable servants! Let's blow away the enemy before us as the Gremory group!" (Volume 12, Life -2)
- "Insulting my servants warrants death!" (Season 2 New)
- "If you can get stronger and feel comfort by touching my breast, then I don’t mind being a Switch-Princess. The Switch-Princess that only belongs to you. If I can become the source of your power, then that will fulfill my wish. –My adorable Ise." (Volume 7, Life-3)
- "You finally called me by my name……… I have waited for this the whole time. I really did…… But I didn’t have the courage to tell you…… So I thought that it would never happen……… But when I heard your feelings that time……… I was so happy……… I was so happy that I was about to cry during the match………" (Volume 10, New Life)
- "A world without him! I don't care about the World without Ise! ……To me, he was….. that person was….. He was more important than anyone else. For me to live without him……" (Volume 12, Life -3)
- The reason why Rias has large breasts even at a young age is because of the blood of the Bael Clan.
- Rias was decided not to have large breasts originally, as Ishibumi said he intended Rias' sizes to be only a bit larger than the common girls in Japan would have. However, he inspected Miyama's illustration of her with big breasts, fell in love with it, and decided to give her large breasts.
- Rias' birthday is April 9th, according to official material.
- According to a questionnaire, her erogenous zone is located on her neck.
- In one of her original early concepts, Rias' design bore a striking resemblance to Tamaki Kousaka from To Heart 2.
- In one of the short stories, it is revealed that Rias is a big "Japanophile", having a huge collection of objects and artifacts back in her room in the Underworld.
- It is also the reason as to why she came to visit Japan in the first place.
- Rias mentioned that she wants a Japanese style wedding when she gets married and wants it in the Human world; possibly due to her being a Japanophile.
- Rias wants to have her wedding take place in Kyoto.
- Rias' name is derived from the Pokémon Garchomp ((Japanese: ガブリアス Gaburias). 
- The reason for this is because Ishibumi decided she must have a foreign name from the beginning.
- Rias is known as one of the "Rookies Four" along with Sairaorg, Sona, and Seekvaira.
- The other name for them is "The Four Novice Kings".
- Rias is the character that killed the most named characters in the series for a total of five characters (Raynare, Dohnaseek, Kalawarner, Mittelt, and Viser).
- Rias has a fear of camels; this occurs when she got hurt by wild camels after she sneaked out to go to the farm when she was still young.
- The Crimson Extinct Dragonar was inspired by the Extremis Iron Man Armor
- Originally, Rias wasn't even planned to be in the series.
- Ishibumi describes Rias as being the King, the mother, and the big sister of her peerage all at once.
- Rias's nickname Crimson-Haired Ruin Princess was taken from her mother's nickname Flaxen-haired Ruin Princess.
- Rias could play the piano when she was a child but it is unknown if she still can.
- Rias makes review videos of her “Switch Princess goods” and uploads them to DeviTube, with the accessories she wears in them secretly becoming popular as a compelling fashion choice.
- Rias is the first female character to be placed into an engagement, the second being Kiyome, and third being Rossweisse.
- Rias has a driving license.
- She owns multiple cars such as a red saloon and a red convertible being two of them.
- Rias had a dream of going on a drive date with Issei which finally came true.